The present invention is directed to vehicles. More particularly, the invention provides gantry crane vehicles and methods thereof. Merely by way of example, the invention has been applied to installation and operation of photovoltaic arrays. But it would be recognized that the invention has a much broader range of applicability.
Photovoltaics convert sunlight into electricity, providing a desirable source of clean energy. FIG. 1 is a simplified diagram of a conventional photovoltaic array. The photovoltaic array 100 includes strings 1, 2, 3, 4, . . . n, where n is a positive integer larger than or equal to 1. Each string includes photovoltaic (PV) modules (e.g., solar panels) that are connected in series. The photovoltaic array 100 is connected to a central inverter 110, which provides an alternating current (AC) connection to a power grid 120. FIG. 2 is a simplified diagram of a conventional photovoltaic module. The photovoltaic (PV) module 210 includes a junction box 220 on the backside of the PV module 210.
The installation of photovoltaic arrays often presents logistical challenges. Not only does the site for the photovoltaic array need to be properly prepared, but large quantities of materials also need to be transported to and within the site. For example, the site for the photovoltaic array may have existing vegetation that would interfere with the installation and operation of the photovoltaic array. This vegetation usually has to be cleared. The site may also have uneven terrain that usually requires extensive grading and earth moving. Once the site is prepared, it is then often necessary to build an extensive infrastructure on which the strings of PV modules 210 are to be affixed. The PV modules 210 are then moved into position, affixed to the structure, and interconnected so that power can be delivered to the power grid 120. Each of these operations can be time-consuming and expensive.
Once the photovoltaic array is in operation, additional infrastructure often is used to support, maintain, evaluate, and repair the array. In order to support the operation of the photovoltaic array, equipment and materials routinely need to be transported from one end of the array to another. For example, the test equipment is transported to a PV module that is under evaluation. In another example, the cleaning equipment is transported to remove debris and dirt from the PV module. In yet another example, an additional module is transported as replacement for the defective module. Depending upon the terrain, soils, and weather, simply getting equipment and materials from one end of the array to another often poses significant challenges, especially if the ground is muddy. As with the installation, these operational needs can also be time-consuming and expensive.
Hence, it is highly desirable to improve techniques for installation and operation of photovoltaic arrays.